于家堡枢纽站房南段地下结构体系研究

研究目的:天津于家堡枢纽站房南段地下结构为地下火车站,位于长轴跨度143m的贝壳形钢结构网壳下,站台不设柱。为解决重载、大跨、顶板上下结构柱网不对应、上部网壳水平荷载大、顶板超大开洞、洞边板大跨悬臂等技术难点,需对结构体系进行研究。借助有限元,对拱形和框架两种结构体系进行分析。研究结论:(1)与框架体系相比,拱形体系顶梁弯矩小,但主要构件仍超出了钢筋混凝土的承载能力。(2)由于柱距大且不均匀、顶板超大开洞,拱形体系顶梁受拉严重。(3)内拱外平断面的拱效应不如从其下边缘起拱的真正拱。(4)针对于家堡枢纽南段地下结构的特点,框架体系优于拱形体系。

Research on Underground Structure System of South Part of Yujiapu Railway Transition Junction

Research purposes:Tianjin Yujiapu underground railway station without columns in the platform supports a single-layer conch-shaped steel shell which is 143 meters in span.To resolve the difficulties such as heavy load,large span,bearing shell supports which are not on the columns,great horizontal loads of shell on the underground structure,absence of most of the top plate under the shell and large span cantilever plate besides the great elliptic hole,underground structure system must be elaborately researched.Finite element method is applied on the research of two structure systems including frame structure and arch structure. Research conclusions:(1) Although the top beam moments of arch system are much smaller than that of frame system,the concrete structure is still not capable enough for the main beams.(2) Large tension axial forces are caused in beams by large span of beams,different distance of columns and absence of most of the top plate under the shell.(3) The section of the arch is designed as plat top and arch bottom to support the shell,while its arch effect is weaken.(4) Consider the features of Yujiapu station,frame structure is more reasonable than arch structure.